JPH0465358A - Method for manufacturing carbon fiber reinforced carbon material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing a high-strength carbon fiber-reinforced carbon material having excellent physical properties such as heat resistance, chemical resistance, abrasion resistance, and light weight. .

(Prior art) Methods for producing carbon fiber-reinforced carbon materials using prepreg are broadly divided into resin impregnation carbonization methods and C to 'D methods, and many improved methods have been proposed (Japanese Patent Laid-Open No. 534011 , JP 58-9070, JP 58-48485, JP 58-79806, JP 62-212263, etc.).

In resin impregnation carbonization method C, thermosetting resins such as furan resins and phenolic resins, and thermoplastic resins mainly represented by pitch are used as carbon raw materials that become the matrix of carbon fiber reinforced carbon materials. ing. This manufacturing process involves impregnating carbon fiber reinforced material as a reinforcing agent (aggregate) with these resins, heating and curing to create a prepreg, and laminating this prepreg to a thickness of about 1000" in an inert atmosphere. A method of carbonizing a matrix resin by heat treatment with C is widely used.

This resin impregnation carbonization method requires an extremely slow temperature increase rate at the temperature at which the resin (including pitch) melts and carbonizes, and the carbonization yield of the resin is low at 40 to 60χ, resulting in the formation of voids due to volatile fractions. There are problems such as the need for a complicated secondary treatment of repeated resin impregnation, carbonization, and compression.

On the other hand, in the CVD method, low carbon number hydrocarbons such as methane, propane, etc. and inert gases such as argon are introduced into the CVD equipment as matrix raw materials, and the
This is a method in which carbon reacted at 1500°C is directly vapor deposited. Since the CVD method deposits pyrolytic carbon directly onto the base material in the vapor phase, it is possible to create a dense and homogeneous matrix or cake, but the equipment cost is high and it takes a long time, which reduces productivity. This is extremely disadvantageous from an economic standpoint.

For this reason, it is usually used in combination with the resin impregnation carbonization method for secondary retention treatment.

(Problems to be Solved by the Invention) The manufacturing process of carbon/carbon composite materials that combine carbon fibers, matrices, and matrix is complicated. In other words, in the production method of carbon fiber-reinforced carbon materials using the above-mentioned conventional technology, complicated post-treatments such as CVD treatment, re-impregnation with resin, and repeated firing are required in order to impart density, which is extremely difficult. It becomes expensive. For this reason, its applications are currently limited, which hinders its use in a wide range of fields.

An object of the present invention is to provide a method for producing a high-strength carbon fiber-reinforced carbon material having excellent physical properties such as heat resistance, chemical resistance, abrasion resistance, and lightness by a simple method and in a short time. That's true.

(Means for Solving the Problems) The inventors focused on the characteristics of mesoface pitch, and as a result of intensive studies to achieve the above objective, they developed a matrix of mesoface pitch that has high impregnability and high carbonization yield. The present inventors have discovered that when used in a carbon fiber-reinforced carbon material, high tackiness can be obtained by heat treatment, and a high-performance carbon fiber-reinforced carbon material can be obtained by a simple method without using a binder, leading to the present invention.

That is, in producing a carbon fiber-reinforced carbon material in which a plurality of prepregs using carbon fiber aggregates are laminated, the present invention provides that the temperature at which the carbon fiber aggregate has a softening point of 350°C or lower and a viscosity of 80 voids is 4o. Below ○℃ and 600℃
A method for producing a carbon fiber reinforced material, characterized in that prepregs melted and impregnated with mesoface pitch with a carbonization yield of 7o% or more and preheated are laminated, pressed without using a binder, and then fired. .

The carbon fiber aggregate used in the present invention includes PAN
Carbon fibers made of various carbon fibers, such as type, pinch type, etc., are used. This carbon fiber aggregate may be any of unidirectional fibers, two-dimensional woven fabrics, and nonwoven fabric sheets, or may be a combination of these, and is determined depending on the use and required characteristics.

This carbon fiber aggregate as a reinforcing material is generally preferably used after surface treatment such as oxidation treatment.The mesoface pitch used as the matrix is
The optically anisotropic phase as measured by a polarizing microscope is at least 80% or more, preferably 9oz or more, more preferably substantially 1
It is desirable that there be 00χ. This mesoface pitch needs to have impregnating properties to the carbon fiber aggregate, and the impregnating property varies depending on the shape of the carbon fiber aggregate, etc.
In general, pitches with low softening points have high impregnation properties, and the softening point of mesoface pitch in the present invention is 350"C or less,
Preferably it is 300°C or less. Further, the temperature at which the viscosity of this pitch becomes 80 voids must be 400° C. or lower.

The softening point is measured using a scanning calorimeter, and the viscosity is measured using a flow tester. When using mesoface pitch with a softening point and viscosity of 80 Boise C higher than these values, the fluidity is low and impregnating properties are reduced, making it impossible to form a dense and homogeneous matrix, resulting in high strength. Carbon material cannot be obtained.

Further, the mesoface pitch used in the present invention has a carbonization yield of 70% or more, preferably 80% or more. This carbonization yield is the carbonization yield when the temperature is gradually raised to 600° C. in an inert gas flow and maintained for about 2 hours. When mesoface pitch with a low carbonization yield is used, voids are likely to be formed due to the volatile fraction in the product, resulting in a decrease in the strength of the resulting carbon fiber reinforced material.

Examples of mesoface pitches that satisfy these conditions include JP-A-1-13621 and JP-A-1-254796.
The mesoface pitch described in No. 1 and Japanese Patent Application No. 1-309842 is suitable. This mesoface pitch is a pi-noti obtained by polymerizing condensed polycyclic aromatic hydrocarbons in the presence of IF-BF3, and it has a high carbonization yield and a low softening point at 200-350℃. Shows good impregnation properties.

2′ mesoface pitch at a temperature higher than the softening point,
For example, the carbon fiber aggregate is impregnated by heating and melting at 200 to 390"C. In order to appropriately adjust the amount of impregnation,
After impregnation, an operation is performed to squeeze out excess pia chi, if necessary.

The pinch-impregnated carbon fiber aggregate thus obtained is then preheated. For the preheating treatment, it is necessary to select appropriate heating conditions so that the mesoface pitch that has penetrated between the fibers does not completely carbonize, does not lose its tackiness, and can further improve the carbonization yield. There is. The conditions for this preheating treatment vary depending on the properties and impregnation rate of the mesoface pitch, but in general, it is
Heating is carried out for a short time from 350 to 490°C at a temperature increase rate of °C/min. The pressure i in the preheating treatment is not particularly limited, and may be normal pressure, increased pressure, or reduced pressure.

If the preliminary heat treatment is insufficient, expansion and foaming due to volatile gas will easily occur in the next laminated carbonization step, making it impossible to obtain a high-performance carbon material. However, by performing oxidation treatment by blowing a small amount of air during or just before the end of the preheating process, it is possible to suppress these expansions and foaming. In addition, due to the slight expansion ζ during the preheating treatment, the material can be densified without losing its adhesive properties by highly filling it by rolling or pressing during the preheating process.

On the other hand, excessive preheating treatment impedes the fusion properties of the prepreg, tends to cause delamination, and a carbon fiber-reinforced carbon material having desired strength may not be obtained. In other words, by appropriately performing the preheating treatment, it is possible to maintain the adhesiveness of the membrane pitch and to exclude as much gas as possible during the carbonization process, resulting in high-density, high-strength carbon fibers that can be produced by firing twice. A reinforced carbon material can be obtained.

Next, the prepregs that maintain this adhesiveness are laminated and pressed. In this case, a binder is not required, and the shape of the laminate may be plate-shaped,
A desired shape such as a cylindrical shape can be freely selected.

Pressing must be carried out within a pressure range that does not destroy the carbon fiber structure of the reinforcing material and do not lose its initial strength. The pressing process can produce a carbon material with high strength even at room temperature in a non-oxidizing atmosphere, but if necessary,
If the temperature is raised to about C, the strength of the carbon material can be further improved.

The desired carbon fiber-reinforced carbon material is manufactured by subsequently firing the laminate obtained by pressing. The firing process is performed by heating the laminate to a temperature of 600 to 1,500°C to carbonize it in a non-oxidizing atmosphere, but there is also a second process that further includes a step of heating this carbide to a temperature of 2,000 to 3,000°C to graphitize it. You can also do it.

(Effects of the Invention) In the present invention, mesoface pitch, which is easy to carbonize and graphitize and has a high carbonization yield, is used as the raw material for the matrix. A sufficiently high density can be obtained. Furthermore, high tackiness can be obtained by performing the preheating treatment of the present invention using mesoface pitch with high impregnability, so no special handker is required. Furthermore, the matrix derived from mesoface pitch has an optically anisotropic structure, has high grain quality, and is highly pure, so that a high-strength carbon fiber reinforced material 4 can be obtained.

According to the present invention, a high-density and high-strength carbon fiber-reinforced carbon material with excellent physical properties such as heat resistance, chemical resistance, abrasion resistance, and lightness can be easily produced in a short time and at low cost for the above reasons. Therefore, the present invention has great industrial significance.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these Examples.

Example I Made of PAN-based carbon carbon fiber woven fabric, trading card cloth #63
43) with acetone, and then polymerized naphthalene in the presence of HF-BF3.
Carbonization yield 85x when heated to 8600'C) was impregnated under reduced pressure at 300'C, and excess pitch was squeezed out through a hot roll.

Next, as a preheating treatment, this impregnated material was heated at a heating rate of 5℃/
The temperature was raised to 370° C. for 20 minutes, and three fusible rings having a carbon fiber content of about 50 wtχ and a fusibility were tuned.

The thus obtained prepregs were laminated without adding a binder and pressed under a nitrogen atmosphere to 500°C using a hot press device (temperature increase rate 1°C/min, maximum press pressure 200kgf/cm2). After sowing, the press pressure was released and the temperature was increased at a rate of 1° (:/min) under an argon atmosphere.
By raising the temperature to 1300℃, the diameter of 60mm,
A carbide with a thickness of 10 mm was obtained.

Example 2 The carbide obtained in Example 1 was further heated under an argon atmosphere.
The temperature was raised to 500°C to obtain a graphitized product.

L Sai Kui↓ Using prepregs similar to those in Example 1, they were laminated without adding a binder and molded at room temperature to a diameter of 60 mm and a thickness of 10 mm (molding pressure 200 Jf/cm2). Thereafter, the temperature was raised to 1300'C under an argon atmosphere at normal pressure to obtain a carbide.

Example 4 The carbide obtained in Example 3 was further treated with 2
The temperature was raised to 500°C to obtain a graphitized product.

Kiln] 1 FIP-BF is added to the carbon fiber nonwoven fabric from which the sizing agent has been removed (Kureka Paper E-20, manufactured by Kureha Chemical Industry ■).

Mesoface pinch obtained by polymerizing naphthalene in the presence of (softening point 285℃ 1 viscosity 80 voids temperature is about 380℃ 1600"C carbonization yield 87χ
) was impregnated at 380° C. under normal pressure, and the excess pinch was squeezed out through a hot roll.

Next, as a preheating treatment, this impregnated material was heated at a heating rate of 5℃/
By raising the temperature to 430°C at min and holding it for 10 minutes, a bleb rig having a carbon fiber content of about 50 wtχ and a fusion property was prepared.

This prepreg was laminated without adding a binder, and 100
After real pressing at 500° C. under a pressure of kgf/cm 2 , carbonization was performed at 1300° C. under normal pressure to obtain a carbide with a diameter of 60 mm and a thickness of 10 mm.

Example 6 The carbide obtained in Example 5 was further heated under an argon atmosphere.
The temperature was raised to 500°C to obtain a graphitized product.

The evaluation results of carbides obtained in each example are shown below.

Patent applicant: Mitsubishi Gas Chemical Co., Ltd. Agent: Patent Attorney Sadafumi Kohori hand Continued Supplementary Positive book (spontaneous) 6゜ Contents of correction

Claims (3)

[Claims] (1) When manufacturing a carbon fiber-reinforced carbon material made by laminating multiple prepregs using carbon fiber aggregates, the temperature at which the carbon fiber aggregate has a softening point of 350°C or lower and a viscosity of 80 poise is 400°C or lower A carbon fiber-reinforced material characterized by laminating prepregs melt-impregnated with mesoface pitch and preheated and having a carbonization yield of 70% or more at 600°C, pressed without using a binder, and then fired. Production method (2) Perform the preliminary heat treatment step in a non-oxidizing atmosphere for 350~
The method for producing a carbon fiber reinforced material according to claim 1, which is carried out at a temperature of 490°C. (3) Pressing process at 300-600℃ in a non-oxidizing atmosphere
The method for manufacturing a carbon fiber reinforced material according to claim 1, wherein the firing step (4) is performed by heating the pressed laminate for 600 minutes in a non-oxidizing atmosphere.
Carbonization at a temperature of ~1500°C, or even 200°C
The method for producing a carbon fiber reinforced material according to claim 1, which comprises a step of graphitizing at a temperature of 0 to 3000°C.